Effects of drought and vegetation management on the establishment of 3 tree species in Northamptonshire, England

Water is a limiting factor in the distribution and growth of trees. Changing climatic conditions are likely to significantly effect tree species development. The planting and establishment of trees needs to take into account these changing factors in terms of design and species selection. This study looked at survival and growth of newly planted trees under field scale conditions and the effects of soil water availability and ground treatments. The experiment followed a blocked plan allowing a line source design to irrigate three tree species, ash, Douglas fir and oak. Each plot of 90 trees was divided into 5 irrigation subplots with varying levels of water application. Two ground treatments, bare ground and vegetated were also applied. Over a three year period, there was a significant effect of species (P<0.001) and herbicide application (P<0.01) on tree survival. Tree height and diameter were significant (P<0.01) between species and herbicide. Irrigation had a significant effect on growth rates of all species with no effect on survival. Ground vegetation biomass significantly increased in high irrigation subplots (P<0.01), with increasing festuca rubra dominance decreasing plant diversity (R2=0.8533). The results suggest that soil moisture availability increases tree growth but does not significantly improve survival rates of the tree species studied. Water is a key factor in the establishment of trees with maintained soil moisture increasing growth development of individuals. Therefore site and species selection are essential in the design of woodland plantings for conservation, recreation and commercial activities.